Wire-based analog telephone services (i.e., plain old telephone services, or POTS) are generally provided between the telephone company's central office (CO) and individual customers using twisted pairs of copper wire. Due to interference and signal loss, POTS transmission over copper wire is feasible only up to a maximum length of about 18,000 feet. For those customers situated within about 18,000 feet of the CO, the twisted pairs of copper wire may be directly connected between the customer's individual termination point (or outlet) and a service switching point (SSP) within the CO.
A digital loop carrier (DLC), housed in a remote terminal (RT) cabinet, is used to provide POTS to customers situated more than 18,000 feet from the CO. As shown in FIG. 1, in a DLC system a fiber optic cable 81 runs between the CO 79 and the DLC 80 which may be located well over twenty-five miles from the CO. Customers may be located up to about 12,000 feet from the RT and are connected to the DLC via twisted pair copper wires. As a safety measure, the copper wiring 83 from the customer is electrically connected to an individual protector socket 84 on the lightning protector block 75. The protector socket 84 is electrically connected to the DLC via splices in the wiring 82 between the socket and the DLC. A lightning protector, or fuse (not shown) is plugged into the individual protector socket 84 to complete the circuit between that customer's wires and the POTS from the DLC.
FIG. 2a is an enlarged schematic diagram of the electrical connections terminated on protector socket 84. Wires 82 from the DLC to protector block 75 individually terminate at prong holes 1 and 2 of a single protector socket 84. Similarly, wires 83, to the customer, individually terminate at prong holes 3 and 4 of the protector socket. A separate wire 77 terminates at ground 76 on one end and terminates at prong hole 5 of protector socket 84 at the other end.
The circuit between the FDI and the DLC is open (FIG. 2a) unless the protector 65 is plugged in (FIG. 2b). More specifically, there is no electrical connection between prong holes 1 and 3 and between prong holes 2 and 4 unless the protector is in place. FIG. 2b shows the electrical connections established on the protector block when the protector is plugged in. In the event of a power surge, as in the case of a lightning strike, the protector will open the circuits and divert the surge to ground as shown in FIG. 2c.
RT and DLC configurations are sometimes used even when the customers are within the 18,000 foot limit for transmission over copper wire. For example, fiber optic cables may be used to reduce the amount of wires running to and from the CO. Fiber optic cables may also be used to connect new customers in concentrated areas such as in new housing sub-divisions. This lowers the initial costs by reducing the amount of copper wiring and installation hours required. The result is that millions of telecommunications customers in the United States are currently served via RTs.
Due to the high demand for additional features and increased bandwidth requirements, POTS services are presently giving way to high-speed digital telecommunications services. To maximize returns on substantial investments in the current infrastructure, it is often desirable to utilize the existing copper wiring for deploying such new services. An example of one such new service is the Asymmetrical Digital Subscriber Line (ADSL) which provides customers with high speed connections to their Internet Service Providers (ISP) over the same twisted pair copper wiring that is used to provide POTS.
POTS from the SSP must be redirected to a multiplexer for combining the new signal (e.g., the ADSL signal) with POTS to output a single combined signal. This combined signal is then transmitted from the multiplexer to the customer's outlet over the existing copper wiring. If a customer is directly connected to the SSP, installing a new service involves moving the customer's line from the SSP to the multiplexer and connecting the multiplexer to the SSP.
The multiplexer will vary depending on the type of new service offered. For example, a Digital Subscriber Line Access Multiplexer (DSLAM) is commonly used with ADSL services. As described above, the DSLAM is positioned between the customer and the SSP. The DSLAM receives a data circuit (needed for ADSL) from the ISP and a dial tone (needed for POTS) from the SSP and combines the two signals. The DSLAM then outputs the combined dial tone and data over a single pair of copper wires to the customer's termination point. If the installation is made correctly, the interruption of POTS service is of short duration and is limited to the customer subscribing to the new service.
Providing new services (e.g., ADSL) for those customers connected to the CO via DLC requires inserting a multiplexer between the DLC and the customer. This additional multiplexing equipment must have lightning protection to prevent lightning damage. One way to do this would be to install additional lightning protectors in the RT. However, the preferred solution is to use the existing protectors because of the limited availability of space in the RT. FIG. 3 is a schematic showing the electrical connections required.
As shown in FIG. 3, prior to the present invention, the conventional procedure for installing new equipment in the RT required multiple steps: (1) unwrapping the splices joining wires from the protector block to the DLC, (2) pulling apart the wires for the specific customer to be provided the service, (3) adding splices 100 joining the wires between the multiplexer 90 and the DLC, and (4) adding splices 110 joining the multiplexer and the protector block. There are several disadvantages to this installation process.
First, because the existing splice must be opened and pulled apart, other customers' services will be interrupted if their wire pairs are inadvertently pulled apart. Such undesirable interruptions were commonplace when the conventional procedure described above was used. Second, the process requires skilled labor and is time-consuming. For example, even with highly skilled technicians, providing ADSL service to one DLC customer could take up to a half day. Moreover, the manual splicing procedures must be repeated every time a new customer requests ADSL service.
A third disadvantage of the manual splicing method is that once a piece of equipment is manually spliced into the RT, it becomes a relatively permanent fixture and cannot be easily removed or relocated to another RT. This disadvantage may be limited in the case where there are many subscribers to the ADSL service within a single RT. In such case, an RT solution DSLAM (serving up to 192.customers) may be permanently installed. However, as is often the case, many customers will delay subscription to new services when first introduced. Thus, initially only a small percentage of total users will need to be connected. It is more economical to use smaller devices such as a Remote Access Multiplexer (Mini-RAM) which serves, e.g., only 8 customers. As the number of customers subscribing to the new service increases over time, additional Mini-RAMs could be spliced in, but due to limited space in the RT, a more likely solution would be to replace the Mini-RAM with an RT solution DSLAM to accommodate all of the DLC's customers. Removing Mini-RAMs that have been spliced in using prior art methods is costly and time-consuming. It requires the multiple steps of opening splices, removing the equipment and re-splicing wires.
It is an object of the present invention to provide a patch cord and method for installing new equipment, such as a DSLAM or Mini-RAM, into an RT without the need for manually splicing the connections.
It is another object of the present invention is to allow technicians to rapidly install ADSL service for a DLC customer. It is a further object of the present invention to provide a reusable cable for connecting and disconnecting equipment within an RT.